Bilateral Metastatic Gynecomastia from Small-Cell Lung Tumors in a Man: A Report of a Rare Case

A case of a man with the recent onset of painful bilateral firm gynecomastia is reported. Mammography confirmed increased breast density. Biopsy characterized both masses as metastases of a small-cell lung tumor. This case highlights the atypical presentation and complements the literature regarding the rarity of breast metastases from small-cell lung cancer in men. Teaching point: Bilateral gynecomastia in a man with a long history of cigarette smoking should be considered with caution.


INTRODUCTION
Breast metastases from small-cell lung cancer (SLCS) are exceptional in men (0.2%-1.3%) [1,2].Differentiating between a primary small-cell breast tumor and breast metastases of a small-cell lung tumor is a diagnostic challenge given their common morphological characteristics [1,3].This rare case complements the existing scarce literature and highlights the atypical presentation of small-cell lung tumors in males [4].

CASE REPORT
We report the case of a 53-year-old man referred for the exploration of bilateral, painful, and firm breast development, which appeared within 1 month.The patient was known for alcohol abuse and was a longtime smoker.There was no personal or family history of breast cancer.A clinical examination confirmed bilateral gynecomastia with induration.
A mammogram revealed the presence of a macrolobulated retro-nipple opacity bilaterally (Figure 1), measuring 52 × 38 × 50 mm on the right and 50 × 50 × 40 mm on the left, and with blurred posterior contour (white arrow).Both masses were classified as BIRADS 4 (Figure 1).
Ultrasound confirmed the presence of an irregular marginated lobulated hypoechogenic and vascularized masses in both breasts (right Figure 2a; left Figure 2b).Bilateral axillary lymphadenopathy with cortical thickening was also present.
Microbiopsies of the breast masses and cytopuncture of axillary lymphadenopathy revealed breast metastases of a small-cell tumor.
The thoraco-abdominal computed tomography (CT) scan confirmed the presence of a large right upper lobar budding tumor, histologically a small-cell bronchial carcinoma (Figure 3).
The treatment proposed was chemotherapy and immunotherapy.

DISCUSSION
SLCS is an aggressive neuroendocrine tumor that exceptionally metastasizes to the breast (0.2%-1.3%) [1,5].Pulmonary SLCS is often diagnosed incidentally, given its insidious nature [2,6].There are only two cases of bilateral breast metastases from pulmonary SLCS in male patients reported in the literature in 1976 and 2011 [7,3].
Malignancy must be considered in cases of recent-onset gynecomastia associated with smoking [8].In addition, it is imperative to distinguish between a primary breast and metastasized pulmonary SLCS because the therapeutic approach and the prognosis are different [3,9,10].
Although breast metastatic lesions are more superficial and do not cause skin retraction, a distinction between both entities is impossible [1,11].A biopsy is required and the final diagnosis is based on the histological and immunohistochemical analysis, including TTF1 marker, neuroendocrine (NSE, chromogranin A, and synaptophysin), and hormonal receptors [3,10].The TTF-1 marker not being specific on its own.[1].

CONCLUSION
Breast metastases from SLCS are exceptional, especially in male.The distinction between pulmonary and breast small-cell tumors is a diagnostic challenge in imaging.Biopsy and extensive immunohistochemical analyzes are essential for differentiation and therapeutic management.

COMPETING INTERESTS
The authors have no competing interests to declare.

Figure 1
Figure 1 Mammogram with external oblique view of the right breast and the left breast demonstrating an increase in breast density with a macrolobulated shape bilaterally, with blurred posterior contours (white arrowhead) and retronipple topography.No contact with the pectoral muscle.

Figure 3
Figure 3 Thoraco-abdominal CT scan injected into the parenchymal window: left upper lobar mass stenosing the right lobar bronchus and "mass" type breast tissue development, bilaterally.

Figure 2 (
Figure 2 (a) Ultrasound right breast longitudinally.(b) Ultrasound the left breast.Ultrasound confirmed the presence of an irregular marginated lobulated hypoechogenic and vascularized masses in both breasts.